from tkinter import *

coords = [0,0,10,0,10,10,20,10,20,20,0,20]
root = Tk()
root.title("ИТ марафон")
root.geometry("500x500")
canvas = Canvas(bg="white", width=500, height=500)
canvas.pack(anchor=CENTER, expand=1)
canvas.create_polygon(coords)
root.mainloop()